1. Field of the Invention
The present invention relates to a grain retainer construction for an air bag inflator and, more particularly, to such a construction that creates an increased gap between the propellant and the surrounding pressure vessel so that there is reduced heat transfer between them.
2. Description of the Background Art
To secure propellant grains in place in a pressure vessel of an air bag inflator, it is a common practice to utilize “fingers” or elongated retainers which extend through holes in the grains. When the grains are mounted on the retainers, they are normally in contact with or closely adjacent to the wall of the pressure vessel where they are subject to significant heat transfer from the pressure vessel wall when the pressure vessel is exposed to external heat, such as from welding or being exposed to external heat for any other reason. In such known constructions, the propellant grains mounted in the pressure vessel may be subject to auto ignition if the external heat on the pressure vessel exceeds a certain value.
It is important, therefore, to find ways of reducing the heat transfer from the pressure vessel wall to the propellant grains mounted therein to increase the safety of the inflator and also to reduce operating pressures in the pressure vessel by reducing the temperature and burn rate of the propellant grain. The new and improved grain retainer construction of the present invention is not subject to the above described disadvantages and fills the need for a new and improved grain retainer construction that increases the safety of the air bag inflator.